A class of machines exists in the art generally known as scroll machines which are used for the displacement of various types of fluid. The scroll machines can be configured as an expander, a displacement engine, a pump, a compressor etc. and the features of the present invention are applicable to any one of these machines. For purposes of illustration, however, the disclosed embodiment is in the form of a hermetic refrigerant scroll compressor.
Scroll compressors are becoming more and more popular for use as compressors in both refrigeration as well as air conditioning applications due primarily to their capability for extremely efficient operation. Generally, these machines incorporate a pair of intermeshed spiral wraps, one of which is caused to orbit relative to the other so as to define one or more moving chambers which progressively decrease in size as they travel from an outer suction port toward a center discharge port. An electric motor is provided which operates to drive the orbiting scroll member via a suitable drive shaft affixed to the motor rotor. In a hermetic compressor, the bottom of the hermetic shell normally contains an oil sump for lubricating and cooling purposes.
The electric motor typically includes a motor stator which is press fit into a shell of the compressor. The drive shaft is typically press fit to the motor rotor and it is rotatably secured by a main bearing housing and a lower bearing housing. Each bearing housing is also secured to the shell of the compressor. The motor rotor is located within the central bore of the motor stator with a specific clearance being designed between the motor stator and the motor rotor. The toleranced dimension for this clearance is a function of the stator tolerances, the shell tolerances, the two bearing housing tolerances, the driveshaft tolerances and the motor rotor tolerances. Thus, the final dimension for the clearance between the motor rotor and the motor stator can be greater than the optimum clearance desired by the designer of the compressor.
The present invention provides the art with a locating and supporting system which significantly decreases the variance in the clearance dimension between the motor rotor and the motor stator. The tighter control of this clearance increases the operating efficiency of the electric motor. The locating and supporting system includes a bearing housing locating frame which is press fit within the shell and which is supported by the base of the shell. The motor stator is press fit within the frame and the two bearing housings are bolted to the frame. Thus, by accurate machining of the frame the positional relationship between the motor stator and the motor rotor can be accurately controlled and thus the clearance or "air gap" between these two components can be tightly controlled. The tight control of the "air gap" leads to an increased operating efficiency of the electric motor. In addition, the unitization of the bearing housings, stator, rotor and crankshaft with the locating frame simplifies the assembly of the scroll compressor.
Other advantages and objects of the present invention will become apparent to those skilled in the art from the subsequent detailed description, appended claims and drawings.